Cant wear Warrior Hallmark rewardFollow

I just killed the cutthroats and recieved my reward "militia warrior chainmail". SOB i cant equipt it cuz i need a skill of 45 in medium armor. I look at my skills and I have NO entry for that skill. Can someone help me plz plz? What do I do to get or raise that skill? Or, is there a way to upgrade the armor to another skill?.....I'm really confused.

If you have completed the quest but have not hit level 10 yet, you may not be able to wear medium armor.

When you do make it to level 10, you will gain the Medium Armor skill and should be able to equip the item.